In certain types of completions, a bottom assembly such as, for example, gravel pack screens are assembled as part of the liner and a liner top packer and installed in the well bore. Various operations thereafter occur involving specialized equipment. For example, cementing the liner and gravel packing the screens. After the completion of such steps with specialized equipment, the production string is then tagged into the liner-top packer so that production can begin. Due to the multi-stage nature of such operations, prior techniques for mounting auxiliary conduits to the assembly as it is put together at the surface were not workable. For example, in completions where the liner, liner top packer, and production tubing are inserted in a single trip, the auxiliary conduits can be assembled to the liner and production tubing as the assembly is being put together at the surface. With these types of single step installations, the auxiliary conduits could be extended to the desired location without the need to disassemble the auxiliary conduits because subsequent trips would be required for different specialized tools.
As previously stated, where the completion requires multiple steps and trips into the well bore, if auxiliary conduits are to be provided to the producing zone, techniques in the past have not been developed to allow that to occur.
More recently a technique has been developed which is subject to a co-pending patent application which is literally repeated as part of this specification, a technique has been developed to allow auxiliary conduits to be sealingly connected to each other down hole. The availability of this development, to solve a different problem, has opened up a possibility of allowing auxiliary conduits to run down to the producing formations adjacent to the bottom hole assembly. The method of this invention is a procedure whereby such auxiliary conduits can be used in conjunction with a variety of down hole operations such as, for example, gravel pack screens. The auxiliary conduits can be used for a variety of purposes such as actuation of down hole flow control devices, chemical injection, actuation of down hole proppant/chemical injection placement valves, distributed temperature data through fiber optic lines, the disposition of discrete sensors whether electric or fiber, pressure measurements, fluid characterization, and flow rate measurements to name a few. The auxiliary conduits can also be used in the gravel packing operation itself. Stated differently, the method of the present invention allows real time feed back of down hole conditions as certain completion operations are undertaken as well as the ability to sense the formation conditions during production. Accordingly, through the use of fiber optics, one of the objectives of the invention is to sense a variety of data at different times, for example, in a gravel pack completion. The fiber optic cables can be used to sense through pressure impacting them the distribution of the gravel during the gravel packing operation. It can also detect changes in the formation down below during production. Thus, another objective of the invention through the incorporation of the fiber optic technology is to be able to take measurements such as density, impaction, and other physical characteristics of a gravel pack through the use of electrical or fiber optic sensors integrated with screens located in the gravel pack itself. Some of the variables that can be measured with the technique are strain temperature, vibration, pressure, and density to name a few.
Accordingly, it is the objective of the present invention to provide a method whereby auxiliary conduits can be instrumental in the performance of various operations essential to the completion as well as to provide data on a real-time basis of down hole conditions during production particularly in multi-step completion involving multiple trips into the well bore where prior techniques have not allowed auxiliary conduits to extend to the producing zones below a liner top packer, for example.
The following U.S. Patents relate to down hole sensing and also include the use of fiber optics as the sensing devices: U.S. Pat. Nos. 5,925,879; 5,804,713; 5,875,852; 5,892,860; 5,767,411; 5,892,176; 5,723,781; 5,789,662; 5,667,023; 5,579,842; 5,577,559; 5,582,064; 5,570,437; 5,443,119; 5,410,152; 5,386,875; 5,360,066; 5,309,405; 5,252,832; 4,919,201; and 4,783,995.
These patents generally relate to the need to measure parameters in the producing zones of oil, gas, and injection wells. The measurements are used to trace production flow, validate performance of the producing zones, and the equipment installed in those zones, and to optimize production. However, in situations involving multi-trip operations such as a gravel packing a well, such access was unavailable in the previously known devices. In some instances to compensate for this lack of ability to sense in the producing zone, production logging tools or memory logging tools were used. However, running these tools required interruption of production. While these tools provided data, it was only discrete snapshots of the production environment and such information was often provided at a significant direct and indirect cost. Accordingly, one of the objects of the present invention is to provide continuous on demand data to evaluate the performance and health of a well. This is particularly more critical in situations where the completion is complicated as is often used for horizontal and multi-lateral wells.
In the past companies such as Sensor Highway and Pruitt Industries have used control tubes as a means of deploying optical fiber as a distributed temperature sensor, DTS. A pump-down technique has been developed to deploy fiber optic cables in the control tubes. This technique is illustrated in U.S. Pat. No. 5,570,437.
Those skilled in the art will appreciate the scope of the method of the present invention by a description of the preferred embodiment which appears below.